In the case of mufflers, active mufflers and passive mufflers are distinguished. Active mufflers have an electroacoustic converter, which as a rule is formed by a loudspeaker and with which the anti-noise is generated, which with appropriate phase shift leads to a more or less effective cancellation of the sound to be muffled. Using electroacoustic converters, the sound emission can be likewise designed specifically in that certain frequencies are increasingly emitted. In particular, a sound design can be realized with such an active muffler. It is conceivable for example to generate the sound emission of a six-cylinder gasoline engine with a four-cylinder diesel engine.
Such an electroacoustic converter usually comprises a vibratory diaphragm which can be excited into vibrations with the help of an actuator. Furthermore, a cage, which defines the diaphragm and on which the actuator is fastened, is usually provided in addition. With this cage, the converter or the loudspeaker can be fastened to a housing of the muffler.
In contrast with this, a passive muffler works with absorption and/or reflection and/or resonance. Likewise, mixed forms, with which a loudspeaker for active sound attenuation is installed in a passive muffler or with which an active muffler is additionally equipped with resonance and/or absorption and/or reflection chambers, are also realizable in principle.
The present invention deals with the problem of stating an improved embodiment for a muffler of the type mentioned at the outset, which is more preferably characterized by low manufacturing costs and/or by a compact design.